1. Scope of Invention
This invention generally relates to bookbinding and more particularly to a uniquely configured signature, method of folding, and apparatus for folding thereof which increases bookbinding efficiency.
2. Prior Art
Sequentially paged products such as books, pamphlets and magazines derive their origin of manufacture from ancient times, even before movable type, when calligraphic art and hand illuminating art were used by monks to tediously reproduce manuscript pages. The term "signature" is derived from the fact that the calligrapher and hand illuminator of a "quad", a single large sheet containing four to eight pages, identified his work by signing his name to the full sheet containing these pages. Therefore, the original building block of sequential page order still in use is the signature or the process of folding large sheets of paper containing pages into smaller, manageable units so that each page is held in a desired sequential order until bound together.
After the signature-in-the-flat has been completed, they are passed to a folding machine in which the large sheets are folded halfway down their length a number of times until the correct page size for the book and the correct sequence of page numbering is obtained. Thereafter, the folded signatures are placed in receiving hoppers of collating machines or gatherers and are withdrawn one at a time from each of as many hoppers as there are separate signatures in the book. Thus, from each hopper, one signature at a time is withdrawn from the bottom of each stack of signatures in each hopper and deposited on a traveling belt which then moves each signature along to the next hopper where the next signature is deposited on the first and so forth.
By conventional signature folding, this structure affords two important elements, both in the form of what is called the backbone or binding side. The backbone is first used for its multiple layer folded page strength to withdraw each signature one at a time from the bottom of the signature stack within each hopper. The backbone is then utilized to bind the signatures together to form the book.
Three separate methods of combining or binding the signatures together are utilized. The first and most popular method is by simply sewing the stacked signatures together to create combined pages. Another method utilized is "perfect or patent" binding wherein, after gathering, all of the backbones or binding sides are eliminated as by shearing so that the center pages of each signature are exposed. All of the exposed page edges are then joined to each other by applying adhesive thereto. A variation of the perfect or patent binding is entitled "burst binding" in which the folded sheets of each signature have perforations applied to the folded or binding side in an upstream process. These perforations allow certain types of adhesives to penetrate to the center pages. However, this process is limited to certain types of paper and adhesives and is generally limited to certain magazine and catalog productions due to the restrictions on paper, adhesives and drying time. The third method utilizes staples through the backbone in lieu of sewing for relatively small books.
During the signature folding process, each time the sheet must be turned or changed in direction to accommodate a fold orthogonal or perpendicular to the last, the fold speed is reduced considerably. In folding a signature by conventional means as above described, the material must be reoriented for each successive fold. By utilizing the present invention, only one change of direction is required which is estimated to increase press speeds and therefore production by as much as twenty percent (20%).
In addition, the present invention provides for perforations along fold lines in some selected folds so as to completely eliminate the need for a sheering or cutting process of the binding edge prior to effecting gluing thereof in perfect or patent binding. Perforated folds also reduce the size if the signature in the flat for added paper savings.
Downstream operations of each signature assembly require proper orientation so that the background preparation may be completed. This position requires that the folded edge of the assembled signatures normally in the long dimension, be turned to a suitable position for downstream tasks. One type of assembly machine requires that the signatures be reoriented with the backbone facing forwardly in the direction of travel, while other assembly machines require that the gathered signatures be turned or reoriented with the backbone facing rearwardly. My previous U.S. Pat. No. 5,655,866 teaches an improved perforated folded signature. The present invention provides perforated and adhered folds which are adhered together or along either side edge which adapts to either form (web or sheet) of assembly equipment.
By both perforating and adhering multiple webs of preprinted paper material together along at least one of the perforated folds, the multiple webs are stabilized together from relative longitudinal movement therebetween.